In roofing procedures it is well known to cover the roofs of large buildings with moisture impervious single ply sheets, or membranes. Typical industrially used single ply roofing membranes are, e.g., EPDM, an ethylene propylene dimer, TYRIN*, a chlorinated polyethylene, HYPALON, a chlorosulfonated polyethylene, and PVC. In the roofing procedure, large sheets of the material are laid one adjacent another to cover the entire roof, the upper sheets overlapping the lower sheets at their marginal edges. Conventionally, the lapped edges of the roofing membranes are sealed, or bonded together to form a water proof seal. These seals are effected by a) heat seaming for thermoplastics, b) solution adhesives, and c) solid adhesives. Solution adhesives are generally used to seal the roofing membranes in more inaccessible or restricted areas, e.g., around chimneys, vents, or the like. The solution adhesives do not form bonds of strength as great as is characteristic of the heat set seaming process. The necessity of heating the lapped edges can be burdensome, and yet this type of bonding has proven most effective as contrasted with other types of bonds. Consequently, there exists a clear present need for high quality mastic adhesive compositions which do not require the application of heat to bond together the lapped edges of the roofing membranes as in roofing constructions. FNT *TYRIN is a registered trademark of The Dow Chemical Company.